The 2018 Atlantic hurricane season has produced another record after a string of similar strange climate change related excursions during recent years. Meanwhile, at powerful Category 5 storm has formed in the Pacific.
(Mid Ocean Season starts early with Beryl; Pacific cat 5 Maria tracks toward China.)
Beryl, a minimal category 1 storm formed in the tropical convergence zone between Africa and the Caribbean on July 6. According to Brian McNoldy, Beryl is the furthest east-forming pre-August storm on record by a wide margin. With Dorothy being the previous record-holder for earliest storm to form in this region on July 24.
An August-Type Storm in July
The height of the Atlantic hurricane season is known as the Cape Verde Season. During this time, massive clusters of thunderstorms called tropical waves develop over Africa and head out into the tropical North Atlantic. There, they feed on warm sea surfaces and favorable atmospheric conditions — forming into tropical cyclones at a much higher rate than during the rest of the year.
Cape Verde storms typically begin forming in August. And though July does see an increase in tropical wave generation from Africa that can fuel storm formation in the Caribbean and just off the Windward and Leeward Islands in the North Atlantic, we don’t typically see mid ocean forming storms until August.
The odd thing about Beryl is it is acting a lot like an August Cape Verde storm — but a month earlier than is typical. Factors that possibly contributed to Beryl’s early formation include climate change driven warmer than normal sea surfaces in the region, strong clusters of thunderstorms developing over Africa and heading out into the Atlantic at a high rate, and a post-La Nina atmospheric influence that tends to increase the frequency of Atlantic storm formation.
Cat 5 Maria Heading Toward China
Moving over to the western Pacific, we find a very powerful category 5 storm — Maria — moving slowly toward China. Yesterday the storm achieved the highest intensity rating we give for hurricanes as maximum sustained winds surged to 161 mph. The storm has since backed off a bit to just stronger than 155 mph maximum winds. However, it is still a very dangerous system.
Like Beryl, Maria formed over warmer than normal sea surface temperatures — a climate change related factor that provides more fuel for storms. Maria is now tracking off to the north and west. It is expected to cross somewhat cooler waters before heading back into warmer than normal waters off Shanghai. It is thus likely that Maria will see fluctuations in strength as it approaches the China mainland over the coming week.
Overall, climate change’s influence on tropical cyclones is that a human-warmed climate is increasing the peak intensity of the most powerful storms. In addition, alterations in ocean heat and energy balance is moving the zones and changing the times during which storms form. We are thus seeing storms that form out of season and outside of typical climate zones. These shifts and these increases in peak intensity will continue so long as fossil fuel burning and related carbon emissions do not abate.